A device and arrangement method for real-time sensing of internal humidity of dam concrete

Abstract

The present invention discloses a device and arrangement method for sensing the internal humidity of dam concrete in real time, comprising a protective shell, wherein the protective shell is made of concrete material of the dam to be measured, the protective shell comprises an upper cavity and a lower cavity, a partition is provided between the upper cavity and the lower cavity, a temperature and humidity sensor is provided in the upper cavity, and there is a gap between the bottom of the temperature and humidity sensor and the partition; the present invention can effectively and stably measure the internal humidity data of concrete for a long time, can be arranged quickly and conveniently, and effectively avoids damage to the measuring equipment during concrete pouring construction, provides data support for exploring the humidity distribution and evolution characteristics in concrete, and has positive guiding significance for the prevention and treatment of concrete cracks.

Description

Technical Field

[0001] The invention relates to the technical field of dam concrete construction of water conservancy and hydropower engineering, and in particular to a device for sensing the internal humidity of dam concrete in real time and a layout method thereof. Background Art

[0002] In the construction of water conservancy and hydropower engineering dams, concrete is one of the most common and largest-volume materials. Dam concrete has many construction difficulties, such as large and complex structure, difficulty in continuous seamless construction and pouring, high temperature control difficulty, easy expansion and deformation of the mold, which can easily lead to undesirable cracks in the structure, and the main ones are temperature and humidity cracks. This cracking phenomenon will seriously affect the structural performance and use function of concrete. Therefore, studying the changes in temperature and relative humidity inside concrete is of great significance for preventing cracks in the internal structure of concrete.

[0003] The change of relative humidity and uneven distribution of moisture inside concrete are one of the main reasons for cracking. To accurately study the relative humidity distribution inside concrete, we first need an accurate and effective method and instrument to obtain the humidity data of different parts of concrete at different times in real time. However, due to the limitations of sensor structure and concrete use environment, there is no recognized and effective method to measure the humidity inside concrete at this stage.

[0004] In order to solve the above problems, industry technicians have conducted a lot of exploration and practice from different directions, obtained many different measuring devices and methods, and have also been successfully applied in certain specific environments. However, the application of pre-embedded from the beginning of concrete pouring and real-time monitoring is still relatively rare and immature, and there is still room for improvement. After analysis and summary, the main problems are as follows:

[0005] (1) When pouring concrete for a dam, the slurry will be lifted during the vibration process, producing a large amount of flowing slurry. Currently, existing sensors for measuring relative humidity have electronic components such as chips inside. When working, these chips and components can sense the humidity changes in the cavity to obtain data. Therefore, on the one hand, the measuring device is required to have good air permeability and respond to humidity changes in a timely manner. It is best if the response time is consistent with that of the concrete to be measured. On the other hand, the measuring device is required to have good waterproof performance. Once the water in the slurry enters the sensor, it will cause the components to be soaked in water, short-circuit and corrode, which will cause inaccurate readings at the least and direct damage to the sensor at the worst.

[0006] (2) The existing sensors for measuring relative humidity will be affected by drift due to long-term operation in such a high humidity environment. If they are directly used to measure the relative humidity of dam concrete, the accuracy will be difficult to control. Because before the initial setting of the dam concrete, the concrete is rich in water. At this time, the internal relative humidity will be close to 100% and remain high for a period of time. Under normal circumstances, after the initial setting of the concrete, the water will be quickly consumed under the action of the internal hydration heat, and the relative humidity will also drop accordingly, which will not affect the sensor. However, it is difficult for the existing devices for measuring concrete humidity to be waterproof while maintaining air permeability, or the water vapor entering the measuring cavity cannot be quickly and smoothly diffused into the surrounding concrete. Long-term operation in a high humidity environment will cause the sensor data to be false and cannot truly reflect the internal humidity state of the concrete.

[0007] (3) The dam concrete is huge, and the construction time in cold regions is short and the construction period is tight. The task is heavy, and the concrete pouring adopts mechanized rapid construction. The warehousing and vibration are easy to cause damage and destruction to the embedded sensor components, affecting the long-term use and stability of signal transmission, so the humidity sensor needs to be protected.

[0008] (4) Traditional sensor protection measures are based on protecting the sensor. To ensure the normal operation of internal components, a protective shell made of plastic or metal is added to the outside. However, while these measures protect the sensor, they also affect the actual data measured by the sensor and cannot truly reflect the internal temperature and humidity status.

[0009] (5) Most traditional sensors for measuring humidity in the air do not have waterproof measures, and the protection measures for the sensors only provide a stable space for internal measurements and cannot effectively protect the sensors. Summary of the invention

[0010] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a device and arrangement method for real-time sensing of the internal humidity of dam concrete, which can effectively measure the internal humidity data of concrete for a long time, and the humidity data can change in real time with the internal humidity, providing parameter basis for the study of humidity distribution and service life in concrete, and can be quickly and conveniently arranged in combination with the concrete pouring construction process, and effectively avoid the phenomenon of damage to the measuring device during concrete pouring construction.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is: a device for real-time sensing of the internal humidity of dam concrete, comprising a protective shell, the protective shell is made of the dam concrete material to be tested, the protective shell comprises an upper cavity and a lower cavity, a partition is provided between the upper cavity and the lower cavity, a temperature and humidity sensor is arranged in the upper cavity, and there is a gap between the bottom of the temperature and humidity sensor and the partition.

[0012] Preferably, a metal frame is preset in the protective shell.

[0013] Preferably, the data line of the temperature and humidity sensor is connected to a data storage device, and the data storage device is connected to a data processing and analysis system.

[0014] Preferably, a sealing material is also provided on the top of the upper cavity.

[0015] Preferably, a plastic ring is further provided between the outer surface of the temperature and humidity sensor and the inner wall of the upper cavity, and the plastic ring is sleeved on the outer surface of the temperature and humidity sensor.

[0016] In addition, the present invention also discloses a method for arranging the above-mentioned device for real-time sensing of the internal humidity of dam concrete, which comprises the following steps:

[0017] S1: Determine the composition and proportion of construction concrete according to design requirements;

[0018] S2: Use construction concrete to make a protective shell with the same composition and proportion of concrete material;

[0019] S3: Place the temperature and humidity sensor into the protective housing;

[0020] S4: sealing the protective housing and the temperature and humidity sensor;

[0021] S5: Before the construction concrete pouring is completed, the protective shell and the temperature and humidity sensor are arranged, connected to the data storage device through the data cable, and the data is debugged through the data processing and analysis system to perform data processing and analysis.

[0022] Preferably, the step S2 specifically includes the following steps:

[0023] A PVC tube is selected as a mold, and the PVC tube is cut in the middle along the normal direction to form two semi-cylindrical shells, and then transparent tape is used to wrap the surface from the bottom to the top to restore it, and the bottom is blocked with a lower cylindrical rubber plug, and then a metal skeleton is inserted into the PVC tube. Before pouring, the inside of the mold is coated with salad oil to facilitate demolding. While pouring the slurry from the upper end, it is continuously vibrated from the outside to vibrate the internal gas out. After the internal slurry is vibrated and compacted, the top is blocked with an upper cylindrical rubber plug, and then the upper and lower cylindrical rubber plugs are fixed with metal hoops, and the vibration is repeatedly struck from the outside of the upper and lower ends until the internal slurry is vibrated evenly; after the concrete solidifies, the transparent tape is removed, the two semi-cylindrical shells of the PVC tube are separated, and the metal hoop fixing and the upper and lower cylindrical rubber plugs are pulled out;

[0024] Choose a protective shell that is waterproof when placed in water for a long time.

[0025] Preferably, the step S3 specifically includes the following steps:

[0026] Put a plastic ring on the surface of the temperature and humidity sensor to prevent the temperature and humidity sensor from contacting the concrete around the protective shell, and to ensure that there is a gap between the sensor and the partition inside the protective shell and the structure is stable; at the same time, pass the data line at the tail of the temperature and humidity sensor out from the open end at the top of the protective shell.

[0027] Preferably, step S4 specifically includes the following steps:

[0028] A sealing material is used to seal the gap between the tail of the temperature and humidity sensor and the top opening of the protective shell.

[0029] Beneficial effects of the present invention:

[0030] 1. The present invention can measure the internal humidity data of concrete effectively and stably for a long time, can be arranged quickly and conveniently, and effectively avoids damage to the measuring equipment during concrete pouring construction. It provides data support for the study of humidity distribution and evolution characteristics in concrete, and has positive guiding significance for the prevention and control of concrete cracks.

[0031] 2. The present invention uses a temperature and humidity integrated sensor, which is more accurate and comprehensive than the data measured by the temperature and humidity sensor. The sensor uses a high-precision sensor core to ensure its high reliability and long-term stability. At the same time, the metal protective shell is removed, and the protective shell also protects the sensor chip from damage. The measurement data of temperature and humidity are accurate, sensitive, and have a larger measurement and control range.

[0032] 3. When the protective shell in the present invention is cast, a cylindrical metal skeleton structure is placed inside to increase the strength of the protective shell and the stability of the structure. This can prevent the concrete from being squeezed, deformed and damaged during the pouring construction, and prevent the aggregate from colliding and squeezing the temperature and humidity sensor during feeding and vibration, thereby protecting the internal temperature and humidity sensor.

[0033] 4. The protective shell in the present invention is a concrete protective shell made by mixing concrete according to the composition and proportion of the concrete to be tested. Its special structure has a cavity reserved at the bottom, which can effectively prevent the direct entry of moisture inside the concrete, and enable the protective shell to effectively conduct the water vapor inside the concrete while protecting the sensor, thereby ensuring that the sensor will not work in a high humidity environment for a long time, effectively preventing the sensor from being damaged.

[0034] 5. The device of the present invention puts the protective shell into water to soak in advance to test the water seepage effect. Because the concrete protective shell has the function of anti-water seepage after solidification, it can prevent external liquid water from passing through and entering the protective shell, and effectively prevent liquid water from directly flooding the internal temperature and humidity sensor and making its measurement insensitive. Therefore, after testing the water seepage effect, it can protect the temperature and humidity sensors and ensure the accuracy of the humidity measurement results.

[0035] 6. The device of the present invention can put a plastic ring in the middle of the sensor chip inside the protective shell in advance to reduce the impact of the inner wall of the protective shell on the chip. The sensor chip is in a suspended state, which not only reduces the possibility of being submerged in water, but also further improves the sensitivity of the sensor.

[0036] 7. The connection between the protective shell and the sensor chip of the device of the present invention is sealed with high-performance silicone structural sealing materials or epoxy resin materials, which can effectively prevent moisture from entering the protective shell from the top while not conducting heat, thereby reducing the impact on the temperature and humidity of the sensor.

[0037] 8. Since the device is arranged vertically in the concrete, the cavity structure at the bottom of the protective shell can accommodate a small amount of moisture and prevent moisture from directly penetrating into the protective shell from the bottom upward, ensuring that only gas rises into the interior of the protective shell, reducing the risk of the internal temperature and humidity sensor being soaked in water, and further protecting it; in addition, the bottom cavity allows a larger conversion space for internal and external moisture, so that the moisture in the gap slowly penetrates into the bottom cavity of the protective shell due to its own weight, reducing the moisture in the gap, allowing the probe part of the temperature and humidity sensor to fully contact the gas in the gap, making the measurement process faster and the measurement results more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a structural schematic diagram of a device for sensing the internal humidity of dam concrete in real time;

[0039] Figure 2 for Figure 1 A schematic diagram of the three-dimensional structure of the middle protective shell;

[0040] Figure 3 for Figure 2 A vertical cross-sectional structural schematic diagram of ;

[0041] Figure 4 A schematic diagram of the mold structure for making a protective shell;

[0042] Figure 5 It is a schematic diagram of the structure of the temperature and humidity sensor and the protective housing arranged in concrete;

[0043] Figure 6 Schematic diagram of humidity changes over time in the same test block of protective shells made of concrete with different mix ratios. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0045] like Figures 1 to 5 As shown, a device for real-time sensing of the internal humidity of dam concrete includes a protective shell 1, the protective shell 1 is made of the dam concrete material to be tested, the protective shell 1 includes an upper cavity 1.1 and a lower cavity 1.2, a partition 1.3 is provided between the upper cavity 1.1 and the lower cavity 1.2, a temperature and humidity sensor 2 is arranged in the upper cavity 1.1, and there is a gap between the bottom of the temperature and humidity sensor 2 and the partition 1.3. In this embodiment, the protective shell is a special cylindrical structure with two openings at both ends that are not completely through. Because the circular shape has the strongest anti-extrusion ability, a circular structure is adopted. The upper end opening is deeper, with a cylindrical groove that shrinks 30mm downward, the lower end opening is shallower, with a cylindrical groove that shrinks 20mm upward, and a partition support structure in the middle, the interlayer is 10mm thick, the overall structure is 60mm long, the inner diameter is 15mm, and the outer diameter is 25mm. The cavity structure at the lower end of the protective shell is shorter, and there is an independent space that can accommodate a small amount of moisture, so that there is a larger conversion space for internal and external moisture, reducing the risk of the internal humidity sensor being soaked in water. The upper cavity structure is slightly longer than the sensor chip, so the humidity sensor chip can be completely placed inside to prevent the humidity sensor from being submerged and further protect it. The moisture in the gap can slowly penetrate into the lower cavity of the protective shell due to its own weight, reducing the moisture in the gap and making the probe part of the humidity sensor fully contact with the gas in the gap. The middle partition can prevent the moisture in the slurry from directly penetrating into the protective shell from the bottom to the top, ensuring that only the gas rises into the protective shell.

[0046] In this embodiment, when the protective shell 1 adopts a structure with one end open and the other end normal solid, the temperature inside the concrete can be quickly transmitted from the surroundings and the top, but the temperature and humidity response time at the bottom is longer, and there are errors in the transmission. When the bottom is blocked, if water leakage occurs inside, the moisture cannot be dissipated, and there is a high probability that the accuracy of the temperature and humidity sensor will be destroyed.

[0047] When the protective shell 1 adopts a structure with the same openings at both ends, there are cavities at the upper and lower ends, the space is increased, and the internal temperature and humidity are transmitted rapidly. However, since the two ends have the same inward expansion length, the thickness of the internal middle partition is too large or cannot be formed, resulting in the inability to effectively dissipate moisture, or the middle partition is too thin to be formed, and it is also impossible to prevent the slurry at the lower end from penetrating upward.

[0048] In order to solve the above-mentioned problems, a partitioned structure with two openings at both ends is selected, with a deeper retraction at the upper end and a shallower retraction at the lower end. The cavity structure at the lower end of the protective shell of this structure is shorter, and there is an independent space that can accommodate a small amount of water, so that there is a larger conversion space for internal and external water, reducing the risk of the internal humidity sensor being soaked in water. The upper cavity structure is slightly longer than the sensor chip, so the humidity sensor chip can be placed inside to avoid the humidity sensor from being submerged and further protect it. The moisture in the gap can slowly penetrate into the cavity at the lower end of the protective shell due to its own weight, reducing the moisture in the gap and allowing the probe part of the humidity sensor to fully contact the gas in the gap. The middle partition layer can prevent the moisture in the slurry from directly penetrating into the protective shell from the bottom to the top, ensuring that only gas rises into the interior of the protective shell.

[0049] Preferably, a metal skeleton 3 is also preset in the protective shell 1. During concrete pouring and vibration, large aggregates will squeeze the measuring device. It is difficult to completely resist the external force by relying solely on a thin layer of concrete material shell, and it may break and crack. The moisture in the slurry enters and directly contacts the sensor components, causing a short circuit and damaging the sensor. Therefore, it is necessary to set up a metal skeleton inside. After many tests, the metal skeleton material can be made of mesh gaps of 2mm, 5mm, and 10mm. The adhesion ability of meshes with different gaps to concrete slurry is different, and the structural strength and stability are also very different. The metal wire mesh with a wire diameter of 0.5mm and a mesh of 2mm is loose and easy to bend, and the metal skeleton has low strength and is easy to deform. And the gap is small, it is not easy to adhere to the slurry, and the outer layer is easy to fall off during vibration. The metal wire mesh with a wire diameter of 0.5mm and a mesh of 5mm is soft and easy to bend. The manufactured metal skeleton is put into the mold to make the protective shell structure complete, but the strength is still insufficient, the gap is small, the outer surface of the protective shell is dense, water vapor cannot penetrate, and the internal humidity is too low. The metal mesh with a wire diameter of 1mm and a mesh of 10mm is welded by splicing fine wires, and has a stable structure and high strength. It is made into a metal skeleton with large gaps, which can well hang the slurry. The shape is complete, the strength is high, and the structure is stable. In order to support the stability of the internal structure, ensure the strength of the external protective shell, and meet the adhesion of the slurry, the metal skeleton is welded with a metal mesh with a wire diameter of 1mm and a mesh of 10mm.

[0050] Preferably, the data line 2.1 of the temperature and humidity sensor 2 is connected to the data storage device 4, and the data storage device 4 is connected to the data processing and analysis system 5. The data storage device 4 can be a paperless recorder, such as MIK-R4000D paperless recorder, and the data processing and analysis system 8 is a laptop computer.

[0051] Preferably, a sealing material 6 is further provided on the top of the upper cavity 1.1.

[0052] Preferably, a plastic ring 7 is further provided between the outer surface of the temperature and humidity sensor 2 and the inner wall of the upper cavity 1.1, and the plastic ring 7 is sleeved on the outer surface of the temperature and humidity sensor 2. In this embodiment, plastic rings are sleeved on the top of the temperature and humidity sensor and one-third from the bottom to the top, and the temperature and humidity sensor is inserted into the center of the interior, with the top flush with the upper cavity and the bottom suspended and fixed inside the cavity so that it does not contact the inner surface wall around the protective shell, further reducing interference with the measurement results, and the joint between the top and the protective shell is sealed with sealant to ensure that the moisture in the concrete slurry does not flow directly into the interior of the protective shell from the top.

[0053] In addition, the present invention also discloses a method for arranging the above-mentioned device for real-time sensing of the internal humidity of dam concrete, which comprises the following steps:

[0054] S1: Determine the composition and proportion of construction concrete according to design requirements;

[0055] S2: Select construction concrete to make a protective shell 1 with the same composition and proportion of concrete material;

[0056] S3: placing the temperature and humidity sensor 2 into the protective housing 1;

[0057] S4: sealing the protective housing 1 and the temperature and humidity sensor 2;

[0058] S5: Before the construction concrete pouring is completed, the protective housing 1 and the temperature and humidity sensor 2 are arranged, connected to the data storage device 4 via a data cable, and the data is debugged through the data processing and analysis system 5 to perform data processing and analysis.

[0059] Preferably, the step S2 specifically includes the following steps:

[0060] A PVC tube 8 is selected as a mold, and the PVC tube 8 is cut open from the middle along the normal direction to form two semi-cylindrical shells, and then the surface is restored from the bottom to the top with transparent glue, and the bottom is blocked with a lower cylindrical rubber plug 9, and then the metal skeleton 3 is inserted into the PVC tube 8. Before pouring, the inside of the mold is coated with salad oil to facilitate demolding. While pouring the slurry from the upper end, it is continuously vibrated from the outside to oscillate the internal gas. After the internal slurry is vibrated and compacted, the top is blocked with an upper cylindrical rubber plug 10, and then the upper cylindrical rubber plug 10 and the lower cylindrical rubber plug 9 are fixed with metal hoops, and the vibration is repeatedly struck from the outside of the upper and lower ends until the internal slurry is vibrated uniformly; after the concrete solidifies, the transparent glue is removed, the two semi-cylindrical shells of the PVC tube 8 are separated, and the metal hoop fixing and the upper cylindrical rubber plug 10 and the lower cylindrical rubber plug 9 are pulled out; the outer protective shell of the temperature and humidity sensor is a cylindrical metal, and the inside is a chip with a width of 1-1.5 cm, and a diameter of 2 to 3 cm and a length of 1.5 cm are selected. A PVC tube with a length of 8 to 10 cm is used as a mold. The PVC tube is cut from the middle along the normal direction to form two semi-cylinders, and then it is restored by wrapping it with transparent tape to facilitate the vibration of the internal gas during pouring. The bottom is blocked with a cylindrical rubber plug slightly thinner than the mold. The cylindrical structure with a protruding length of 1 to 2 cm and a diameter of 1.5 cm in the center is slightly thicker than the sensor to prevent the bottom moisture from directly penetrating into the protective shell and contacting the sensor; a tubular metal skeleton reinforcement structure with a length of 5.5 cm and a diameter of 2 cm slightly thinner than the mold is inserted to prevent the concrete pipe from having poor water permeability due to being too thick, or being too thin to be formed. The slurry is poured from the upper end and vibrated continuously from the outside. After the internal slurry is vibrated and dense, the top is blocked with a cylindrical rubber plug slightly thinner than the model. The protruding length is 2 to 3 cm and the diameter is 1.5 cm, which is slightly thicker than the cylindrical structure of the sensor, so that the structure is stable when the sensor is placed inside. Then the upper and lower rubber plugs are fixed with metal hoops, and the vibration is repeatedly struck from the outside of both ends until the internal slurry is vibrated evenly. Before pouring, the inside of the mold is coated with salad oil to facilitate demolding. Finally, a cylindrical structure with a length of 6 cm, an inner diameter of 1.5 cm, an outer diameter of 2.5 cm, and two ends that are inwardly contracted by 2 cm and 3 cm respectively is made.

[0061] Select a protective shell 1 that does not leak water when placed in water for a long time. In the initial stage of concrete pouring, the internal moisture content is high and the humidity is high, which causes the concrete protective shell to be in a high humidity environment for a long time. In order to prevent the temperature and humidity sensor inside the protective shell from being easily soaked by the infiltrated water, resulting in loss of accuracy, the concrete protective shell needs to have a certain anti-seepage and waterproof performance in a short time. By selecting different concrete ratios and metal mesh skeleton structures with different porosity, the anti-seepage and waterproof requirements at different times can be met. The smaller the pores of the skeleton made of the metal mesh and the larger the ratio, the higher the waterproof performance of the concrete protective shell produced, and the more stable it is. On the contrary, the larger the pores of the skeleton made of the metal mesh and the smaller the ratio, the lower the waterproof performance of the concrete protective shell produced, and the looser it is. In this test example, the pouring time of large-volume concrete is expected to be 10 hours. In order to ensure that there is no water seepage inside the concrete protective shell in the initial stage during pouring, it is necessary to select a concrete protective shell that does not leak water for a long time in the water and is moist inside. Since the concrete mix ratio to be tested was used in this test, a large-pore metal mesh was selected to make the skeleton, and the resulting concrete protective shell had a longer anti-seepage time, which met the design requirements to a great extent.

[0062] Preferably, the step S3 specifically includes the following steps:

[0063] Put a plastic ring 7 on the surface of the temperature and humidity sensor 2 so that the temperature and humidity sensor 2 does not contact the surrounding concrete in the protective shell 1, and there is a gap at the distance from the partition 1.3 in the protective shell 1 and the structure is stable; at the same time, the data line 2.1 at the tail of the temperature and humidity sensor 2 is passed through the open end at the top of the protective shell 1. Specifically, put a plastic ring on the top of the temperature and humidity sensor 2 and one-third of the position from the bottom to the top, so that the temperature and humidity sensor 2 does not contact the inner wall of the surrounding concrete protective shell, which effectively prevents the sensor chip from losing accuracy due to the close contact with the inner wall of the protective shell when water vapor or water penetrates from the surrounding areas. Because the plastic ring is put on the middle part of the temperature and humidity sensor chip, the influence of metal on the internal temperature can be reduced. In addition, the temperature and humidity sensor is placed in the protective shell, there is a gap at the middle partition in the protective shell, the structure is stable, and it is in a suspended state, which can effectively prevent the sensor chip from being directly immersed in water, with a small error, and can protect the sensor chip.

[0064] Preferably, step S4 specifically includes the following steps:

[0065] The gap between the tail of the temperature and humidity sensor 2 and the top opening of the protective shell 1 is sealed with a sealing material 6. Specifically, the present embodiment uses a high-performance silicone structural sealing material to seal the gap between the tail of the temperature and humidity sensor and the top opening of the protective shell, and evenly applies it on the upper end of the sensor chip and wraps it as a whole on the top of the concrete protective shell, which can further prevent the slurry from directly pouring in from the top of the protective shell and submerging the sensor chip.

[0066] Furthermore, the temperature and humidity data corresponding to different monitoring points are recorded, the real-time monitored temperature and humidity data are analyzed and processed, the heating temperature in the equipment is adjusted as the ambient temperature and time change, and a curve distribution diagram is drawn.

[0067] Finally, the distribution diagram of the device in this embodiment in the concrete to be tested is shown in Figure 4 When multiple monitoring devices are in the same layer inside the concrete to be tested, they should be distributed from the outside to the inside according to the design requirements.

[0068] In this embodiment, the humidity sensor is a low-power, high-precision temperature and humidity sensor with an integrated voltage output of HTVxxLPG (0-5V output). Since relative humidity is a function of temperature, temperature seriously affects the relative humidity in a specified space, a temperature and humidity integrated sensor is used. Traditional humidity sensors are resistive and capacitive, including HM1500LF and Preson (4-20mA output) sensors. Due to the large range of concrete humidity and rough construction technology, such sensors cannot perform long-term measurements.

[0069] The protective shell includes a concrete shell and a metal frame. A humidity sensor is installed inside the concrete protective shell, and the outside is in direct contact with the concrete to be tested. The concrete shell has a special structure and is attached to the internal metal frame, which is stable and strong. The metal frame is placed inside the concrete shell and is cylindrical, playing a supporting role inside.

[0070] The concrete protective shell: The internal humidity of the concrete material is uneven and the moisture diffusion rate is different. In order to maintain the same diffusion rate and fast response time as the concrete to be tested and reduce interference with the measurement results, the protective shell is constructed of slurry material with the same mix ratio as the concrete. Its internal metal skeleton plays a supporting role and strengthens the compressive strength of the internal structure of the protective shell.

[0071] During pouring, since the concrete protective shell is in direct contact with the concrete and is made of concrete material with the same proportion, it can quickly absorb moisture in the concrete slurry, making the protective shell in a wetted state and waterproof inside, and synchronously reflecting the internal humidity status in real time.

[0072] After pouring is completed, since the protective shell is in an infiltrated state during pouring, it can directly and synchronously measure the internal humidity of the concrete test block in real time while protecting the sensor, so that the interior of the protective shell and the concrete test block as a whole are in the same breathing state, ensuring that the measured humidity inside the protective shell is consistent with the actual humidity of the concrete test block; it can ensure the normal operation of the sensor while measuring in a high humidity environment and quickly measure internal humidity changes.

[0073] When the concrete is initially set, the concrete test block will quickly consume water due to the internal hydration heat, and the relative humidity inside the concrete protective shell will also decrease without affecting the sensor. As the concrete test block gradually becomes dry, it will steadily absorb moisture inside the protective shell to reduce the humidity, so that the humidity changes inside the concrete protective shell and the concrete test block are synchronized.

[0074] When making a protective shell 1 of the same composition and proportion of concrete material in step S2, the concrete proportions in common engineering projects include primary, secondary, tertiary and quaternary proportions. Different gradations correspond to gravel of different particle sizes. The higher the gradation, the more gravel particle sizes are mixed, and the better the quality of the concrete. Since the concrete used in this experiment is to make a concrete protective shell and gravel cannot be used, the gradation problem is not considered. The sand used in this concrete protective shell is medium sand with a particle size between 0.5mm-0.25mm. Since the concrete protective shell needs to meet the strength requirements of the corresponding concrete mix ratio under different environments, it is necessary to undergo multiple rounds of testing to detect its strength.

[0075] The commonly used concrete cement mix ratios in engineering are: M2.5, M5, M7.5, M10, M15, and M20, among which the ratios of cement to gravel vary from 1:7.25, 1:7.5, 1:6.3, 1:5.27, 1:4.53, and 1:4.03. To ensure the strength requirements of the concrete protective shell, this test will try different ratios based on different ratios of cement to gravel, starting from 1:10, in a way that the strength of the concrete mortar protective shell will be gradually increased, as shown in Table 1.

[0076] Table 1 Concrete mortar protection shell with different proportions

[0077] The concrete gradation (i.e. construction concrete) used in this engineering example meets the experimental requirements and is closer to the gradation with complete structure and uniform stress. In order to ensure more accurate measurement results, it was finally decided to mix the concrete slurry according to the composition and proportion of the concrete to be tested. This allows the protective shell to effectively conduct water vapor inside the concrete while protecting the sensor chip.

[0078] like Figure 6As shown in the figure, the internal humidity of the concrete protective shells made with different ratios and the concrete protective shells made with the concrete ratio to be tested (i.e., construction concrete) in the same test block changes over time. When the cement: sand ratio is 1:10, the internal humidity rises rapidly in the early stage, and the humidity also drops faster during the later solidification, but its internal structure is loose; when the cement: sand ratio is 1:4, the internal humidity reacts slowly in the early stage, and the humidity does not drop for a long time during the later solidification period, and then drops cliff-like, and the internal humidity is disordered; when the concrete ratio to be tested is used, the internal humidity reacts quickly in the early stage, the humidity is stable in the middle, and the humidity drops slowly in the later stage, and the curve changes smoothly; therefore, the concrete protective shell made with the concrete ratio to be tested reacts more quickly to the changes in the internal humidity of the test block, and the data is more accurate and stable.

[0079] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for arranging a device for sensing the internal humidity of dam concrete in real time, the device for sensing the internal humidity of dam concrete in real time comprising a protective shell (1), the protective shell (1) being made of a dam concrete material to be tested, the protective shell (1) comprising an upper cavity (1.1) and a lower cavity (1.2), a partition (1.3) being arranged between the upper cavity (1.1) and the lower cavity (1.2), a temperature and humidity sensor (2) being arranged in the upper cavity (1.1), and a gap being present between the bottom of the temperature and humidity sensor (2) and the partition (1.3); Features: It includes the following steps: S1: Determine the composition and proportion of construction concrete according to design requirements; S2: Select construction concrete and make a protective shell (1) with the same composition and proportion of concrete material; S3: placing the temperature and humidity sensor (2) into the protective housing (1); S4: performing sealing processing between the protective housing (1) and the temperature and humidity sensor (2); S5: Before the construction concrete is poured, the protective housing (1) and the temperature and humidity sensor (2) are arranged, connected to the data storage device (4) via a data cable, and the data is debugged and processed and analyzed via the data processing and analysis system (5); The step S2 specifically includes the following steps: A PVC tube (8) is selected as a mold, and the PVC tube (8) is cut in the middle along the normal direction to form two semi-cylindrical shells, and then the surface is restored from the bottom to the top by wrapping with transparent glue, and the bottom is blocked by a lower cylindrical rubber plug (9), and then the metal skeleton (3) is inserted into the PVC tube (8). Before pouring, the inside of the mold is coated with salad oil to facilitate demolding. While pouring the slurry from the upper end, it is continuously vibrated from the outside to vibrate out the internal gas. After the internal slurry is vibrated and compacted, the top is blocked by an upper cylindrical rubber plug (10), and then the upper cylindrical rubber plug (10) and the lower cylindrical rubber plug (9) are fixed by metal hoops, and the outer sides of the upper and lower ends are repeatedly knocked and vibrated until the internal slurry is vibrated uniformly. After the concrete is solidified, the transparent glue is removed, the two semi-cylindrical shells of the PVC tube (8) are separated, and the metal hoop fixing and the upper cylindrical rubber plug (10) and the lower cylindrical rubber plug (9) are pulled out. Select a protective shell (1) that is waterproof when placed in water for a long time; A metal frame (3) is also preset in the protective shell (1); The data line (2.1) of the temperature and humidity sensor (2) is connected to the data storage device (4), and the data storage device (4) is connected to the data processing and analysis system (5); A sealing material (6) is also provided on the top of the upper cavity (1.1).

2. The method for arranging a device for real-time sensing of internal humidity of dam concrete according to claim 1, Features: A plastic ring (7) is also provided between the outer surface of the temperature and humidity sensor (2) and the inner wall of the upper cavity (1.1), and the plastic ring (7) is sleeved on the outer surface of the temperature and humidity sensor (2).

3. The method for arranging a device for real-time sensing of internal humidity of dam concrete according to claim 2, Features: The step S3 specifically includes the following steps: A plastic ring (7) is put on the surface of the temperature and humidity sensor (2) so that the temperature and humidity sensor (2) does not contact the surrounding concrete inside the protective shell (1), and there is a gap between the temperature and humidity sensor (2) and the partition (1.3) inside the protective shell (1) and the structure is stable; at the same time, the data line (2.1) at the tail of the temperature and humidity sensor (2) is passed out from the open end at the top of the protective shell (1).

4. The method for arranging a device for real-time sensing of internal humidity of dam concrete according to claim 1, Features: The step S4 specifically includes the following steps: A sealing material (6) is used to seal the gap between the tail of the temperature and humidity sensor (2) and the top opening of the protective housing (1).

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